Fretmaster - iPad app - Freeware

Fretmaster can help to lern the notes on the fretboard. It's Easy to use and it's free.

To use it for bouzouki select mandolin and then click on the tune fork icon and alter the tuning to GDAD.

Then click on the play button. You will hear a note and see where it is on the fretboard. Now you have to tip on the correct note name on bottom of the page.